arch/blackfin/kernel/signal.c

   1 /*
   2  * File:         arch/blackfin/kernel/signal.c
   3  * Based on:
   4  * Author:
   5  *
   6  * Created:
   7  * Description:
   8  *
   9  * Modified:
  10  *               Copyright 2004-2006 Analog Devices Inc.
  11  *
  12  * Bugs:         Enter bugs at http://blackfin.uclinux.org/
  13  *
  14  * This program is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program; if not, see the file COPYING, or write
  26  * to the Free Software Foundation, Inc.,
  27  * 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  28  */
  29
  30 #include <linux/signal.h>
  31 #include <linux/syscalls.h>
  32 #include <linux/ptrace.h>
  33 #include <linux/tty.h>
  34 #include <linux/personality.h>
  35 #include <linux/binfmts.h>
  36 #include <linux/freezer.h>
  37 #include <linux/uaccess.h>
  38
  39 #include <asm/cacheflush.h>
  40 #include <asm/ucontext.h>
  41 #include <asm/fixed_code.h>
  42
  43 #define _BLOCKABLE (~(sigmask(SIGKILL) | sigmask(SIGSTOP)))
  44
  45 struct fdpic_func_descriptor {
  46         unsigned long   text;
  47         unsigned long   GOT;
  48 };
  49
  50 struct rt_sigframe {
  51         int sig;
  52         struct siginfo *pinfo;
  53         void *puc;
  54         /* This is no longer needed by the kernel, but unfortunately userspace
  55          * code expects it to be there.  */
  56         char retcode[8];
  57         struct siginfo info;
  58         struct ucontext uc;
  59 };
  60
  61 asmlinkage int sys_sigaltstack(const stack_t __user *uss, stack_t __user *uoss)
  62 {
  63         return do_sigaltstack(uss, uoss, rdusp());
  64 }
  65
  66 static inline int
  67 rt_restore_sigcontext(struct pt_regs *regs, struct sigcontext __user *sc, int *pr0)
  68 {
  69         unsigned long usp = 0;
  70         int err = 0;
  71
  72 #define RESTORE(x) err |= __get_user(regs->x, &sc->sc_##x)
  73
  74         /* restore passed registers */
  75         RESTORE(r0); RESTORE(r1); RESTORE(r2); RESTORE(r3);
  76         RESTORE(r4); RESTORE(r5); RESTORE(r6); RESTORE(r7);
  77         RESTORE(p0); RESTORE(p1); RESTORE(p2); RESTORE(p3);
  78         RESTORE(p4); RESTORE(p5);
  79         err |= __get_user(usp, &sc->sc_usp);
  80         wrusp(usp);
  81         RESTORE(a0w); RESTORE(a1w);
  82         RESTORE(a0x); RESTORE(a1x);
  83         RESTORE(astat);
  84         RESTORE(rets);
  85         RESTORE(pc);
  86         RESTORE(retx);
  87         RESTORE(fp);
  88         RESTORE(i0); RESTORE(i1); RESTORE(i2); RESTORE(i3);
  89         RESTORE(m0); RESTORE(m1); RESTORE(m2); RESTORE(m3);
  90         RESTORE(l0); RESTORE(l1); RESTORE(l2); RESTORE(l3);
  91         RESTORE(b0); RESTORE(b1); RESTORE(b2); RESTORE(b3);
  92         RESTORE(lc0); RESTORE(lc1);
  93         RESTORE(lt0); RESTORE(lt1);
  94         RESTORE(lb0); RESTORE(lb1);
  95         RESTORE(seqstat);
  96
  97         regs->orig_p0 = -1;     /* disable syscall checks */
  98
  99         *pr0 = regs->r0;
 100         return err;
 101 }
 102
 103 asmlinkage int do_rt_sigreturn(unsigned long __unused)
 104 {
 105         struct pt_regs *regs = (struct pt_regs *)__unused;
 106         unsigned long usp = rdusp();
 107         struct rt_sigframe *frame = (struct rt_sigframe *)(usp);
 108         sigset_t set;
 109         int r0;
 110
 111         if (!access_ok(VERIFY_READ, frame, sizeof(*frame)))
 112                 goto badframe;
 113         if (__copy_from_user(&set, &frame->uc.uc_sigmask, sizeof(set)))
 114                 goto badframe;
 115
 116         sigdelsetmask(&set, ~_BLOCKABLE);
 117         spin_lock_irq(&current->sighand->siglock);
 118         current->blocked = set;
 119         recalc_sigpending();
 120         spin_unlock_irq(&current->sighand->siglock);
 121
 122         if (rt_restore_sigcontext(regs, &frame->uc.uc_mcontext, &r0))
 123                 goto badframe;
 124
 125         if (do_sigaltstack(&frame->uc.uc_stack, NULL, regs->usp) == -EFAULT)
 126                 goto badframe;
 127
 128         return r0;
 129
 130  badframe:
 131         force_sig(SIGSEGV, current);
 132         return 0;
 133 }
 134
 135 static inline int rt_setup_sigcontext(struct sigcontext *sc, struct pt_regs *regs)
 136 {
 137         int err = 0;
 138
 139 #define SETUP(x) err |= __put_user(regs->x, &sc->sc_##x)
 140
 141         SETUP(r0); SETUP(r1); SETUP(r2); SETUP(r3);
 142         SETUP(r4); SETUP(r5); SETUP(r6); SETUP(r7);
 143         SETUP(p0); SETUP(p1); SETUP(p2); SETUP(p3);
 144         SETUP(p4); SETUP(p5);
 145         err |= __put_user(rdusp(), &sc->sc_usp);
 146         SETUP(a0w); SETUP(a1w);
 147         SETUP(a0x); SETUP(a1x);
 148         SETUP(astat);
 149         SETUP(rets);
 150         SETUP(pc);
 151         SETUP(retx);
 152         SETUP(fp);
 153         SETUP(i0); SETUP(i1); SETUP(i2); SETUP(i3);
 154         SETUP(m0); SETUP(m1); SETUP(m2); SETUP(m3);
 155         SETUP(l0); SETUP(l1); SETUP(l2); SETUP(l3);
 156         SETUP(b0); SETUP(b1); SETUP(b2); SETUP(b3);
 157         SETUP(lc0); SETUP(lc1);
 158         SETUP(lt0); SETUP(lt1);
 159         SETUP(lb0); SETUP(lb1);
 160         SETUP(seqstat);
 161
 162         return err;
 163 }
 164
 165 static inline void *get_sigframe(struct k_sigaction *ka, struct pt_regs *regs,
 166                                  size_t frame_size)
 167 {
 168         unsigned long usp;
 169
 170         /* Default to using normal stack.  */
 171         usp = rdusp();
 172
 173         /* This is the X/Open sanctioned signal stack switching.  */
 174         if (ka->sa.sa_flags & SA_ONSTACK) {
 175                 if (!on_sig_stack(usp))
 176                         usp = current->sas_ss_sp + current->sas_ss_size;
 177         }
 178         return (void *)((usp - frame_size) & -8UL);
 179 }
 180
 181 static int
 182 setup_rt_frame(int sig, struct k_sigaction *ka, siginfo_t * info,
 183                sigset_t * set, struct pt_regs *regs)
 184 {
 185         struct rt_sigframe *frame;
 186         int err = 0;
 187
 188         frame = get_sigframe(ka, regs, sizeof(*frame));
 189
 190         err |= __put_user((current_thread_info()->exec_domain
 191                            && current_thread_info()->exec_domain->signal_invmap
 192                            && sig < 32
 193                            ? current_thread_info()->exec_domain->
 194                            signal_invmap[sig] : sig), &frame->sig);
 195
 196         err |= __put_user(&frame->info, &frame->pinfo);
 197         err |= __put_user(&frame->uc, &frame->puc);
 198         err |= copy_siginfo_to_user(&frame->info, info);
 199
 200         /* Create the ucontext.  */
 201         err |= __put_user(0, &frame->uc.uc_flags);
 202         err |= __put_user(0, &frame->uc.uc_link);
 203         err |=
 204             __put_user((void *)current->sas_ss_sp, &frame->uc.uc_stack.ss_sp);
 205         err |= __put_user(sas_ss_flags(rdusp()), &frame->uc.uc_stack.ss_flags);
 206         err |= __put_user(current->sas_ss_size, &frame->uc.uc_stack.ss_size);
 207         err |= rt_setup_sigcontext(&frame->uc.uc_mcontext, regs);
 208         err |= copy_to_user(&frame->uc.uc_sigmask, set, sizeof(*set));
 209
 210         if (err)
 211                 goto give_sigsegv;
 212
 213         /* Set up registers for signal handler */
 214         wrusp((unsigned long)frame);
 215         if (current->personality & FDPIC_FUNCPTRS) {
 216                 struct fdpic_func_descriptor __user *funcptr =
 217                         (struct fdpic_func_descriptor *) ka->sa.sa_handler;
 218                 __get_user(regs->pc, &funcptr->text);
 219                 __get_user(regs->p3, &funcptr->GOT);
 220         } else
 221                 regs->pc = (unsigned long)ka->sa.sa_handler;
 222         regs->rets = SIGRETURN_STUB;
 223
 224         regs->r0 = frame->sig;
 225         regs->r1 = (unsigned long)(&frame->info);
 226         regs->r2 = (unsigned long)(&frame->uc);
 227
 228         return 0;
 229
 230  give_sigsegv:
 231         if (sig == SIGSEGV)
 232                 ka->sa.sa_handler = SIG_DFL;
 233         force_sig(SIGSEGV, current);
 234         return -EFAULT;
 235 }
 236
 237 static inline void
 238 handle_restart(struct pt_regs *regs, struct k_sigaction *ka, int has_handler)
 239 {
 240         switch (regs->r0) {
 241         case -ERESTARTNOHAND:
 242                 if (!has_handler)
 243                         goto do_restart;
 244                 regs->r0 = -EINTR;
 245                 break;
 246
 247         case -ERESTARTSYS:
 248                 if (has_handler && !(ka->sa.sa_flags & SA_RESTART)) {
 249                         regs->r0 = -EINTR;
 250                         break;
 251                 }
 252                 /* fallthrough */
 253         case -ERESTARTNOINTR:
 254  do_restart:
 255                 regs->p0 = regs->orig_p0;
 256                 regs->r0 = regs->orig_r0;
 257                 regs->pc -= 2;
 258                 break;
 259         }
 260 }
 261
 262 /*
 263  * OK, we're invoking a handler
 264  */
 265 static int
 266 handle_signal(int sig, siginfo_t *info, struct k_sigaction *ka,
 267               sigset_t *oldset, struct pt_regs *regs)
 268 {
 269         int ret;
 270
 271         /* are we from a system call? to see pt_regs->orig_p0 */
 272         if (regs->orig_p0 >= 0)
 273                 /* If so, check system call restarting.. */
 274                 handle_restart(regs, ka, 1);
 275
 276         /* set up the stack frame */
 277         ret = setup_rt_frame(sig, ka, info, oldset, regs);
 278
 279         if (ret == 0) {
 280                 spin_lock_irq(&current->sighand->siglock);
 281                 sigorsets(&current->blocked, &current->blocked,
 282                           &ka->sa.sa_mask);
 283                 if (!(ka->sa.sa_flags & SA_NODEFER))
 284                         sigaddset(&current->blocked, sig);
 285                 recalc_sigpending();
 286                 spin_unlock_irq(&current->sighand->siglock);
 287         }
 288         return ret;
 289 }
 290
 291 /*
 292  * Note that 'init' is a special process: it doesn't get signals it doesn't
 293  * want to handle. Thus you cannot kill init even with a SIGKILL even by
 294  * mistake.
 295  *
 296  * Note that we go through the signals twice: once to check the signals
 297  * that the kernel can handle, and then we build all the user-level signal
 298  * handling stack-frames in one go after that.
 299  */
 300 asmlinkage void do_signal(struct pt_regs *regs)
 301 {
 302         siginfo_t info;
 303         int signr;
 304         struct k_sigaction ka;
 305         sigset_t *oldset;
 306
 307         current->thread.esp0 = (unsigned long)regs;
 308
 309         if (try_to_freeze())
 310                 goto no_signal;
 311
 312         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 313                 oldset = &current->saved_sigmask;
 314         else
 315                 oldset = &current->blocked;
 316
 317         signr = get_signal_to_deliver(&info, &ka, regs, NULL);
 318         if (signr > 0) {
 319                 /* Whee!  Actually deliver the signal.  */
 320                 if (handle_signal(signr, &info, &ka, oldset, regs) == 0) {
 321                         /* a signal was successfully delivered; the saved
 322                          * sigmask will have been stored in the signal frame,
 323                          * and will be restored by sigreturn, so we can simply
 324                          * clear the TIF_RESTORE_SIGMASK flag */
 325                         if (test_thread_flag(TIF_RESTORE_SIGMASK))
 326                                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 327                 }
 328
 329                 return;
 330         }
 331
 332  no_signal:
 333         /* Did we come from a system call? */
 334         if (regs->orig_p0 >= 0)
 335                 /* Restart the system call - no handlers present */
 336                 handle_restart(regs, NULL, 0);
 337
 338         /* if there's no signal to deliver, we just put the saved sigmask
 339          * back */
 340         if (test_thread_flag(TIF_RESTORE_SIGMASK)) {
 341                 clear_thread_flag(TIF_RESTORE_SIGMASK);
 342                 sigprocmask(SIG_SETMASK, &current->saved_sigmask, NULL);
 343         }
 344 }